Pulse current-assisted roll bonding method for magnesium/titanium composite plate with large thickness ratio

Abstract

A pulse current-assisted roll bonding method for a magnesium/titanium composite plate with a large thickness ratio is provided. The specific steps are as follows: 1, pre-treating a slab; 2, applying a pulse current; 3, rolling and bonding; and 4, post-treating the slab. The magnesium/titanium composite plate with the large thickness ratio is obtained.

What is claimed is: 
     
       1. A pulse current-assisted roll bonding method for a magnesium/titanium composite slab with a large thickness ratio, comprising the following steps:
 step 1, pre-treating a slab: 
 a, cutting a magnesium or magnesium alloy plate with large thickness, an intermediate transition layer foil and a titanium thin plate into slabs with a same length and width dimensions; annealing the slabs of magnesium or magnesium alloy plate with large thickness and the titanium thin plate, preserving heat, cooling the slabs after the annealing step and taking out the slabs after cooling; 
 b, grinding surfaces of each of the slabs with sandpaper until a surface roughness is polished to Ra 1.6-0.8 micrometers, cleaning and drying after the grinding; and 
 c, assembling cleaned slabs according to a sequence of the titanium thin plate, the intermediate transition layer foil and the magnesium or magnesium alloy plate with large thickness; relatively placing polished slabs surfaces with certain roughness, and leaving a small gap between the slabs, wherein the small gap is of 0.03 mm; and carrying out leveling and straightening to obtain a magnesium/titanium composite slab with a large thickness ratio; 
 a thickness of the magnesium or magnesium alloy plate with large thickness is 5-25 mm, a thickness of the titanium thin plate is 0.1-0.5 mm, and a thickness combination ratio of the titanium thin plate to the magnesium or magnesium alloy plate is 1:50; 
 step 2, applying a pulse current: 
 placing the magnesium/titanium composite slab with the large thickness ratio in a semi-closed protective cover equipped with a pulse current-assisted roll device, introducing inert gas, applying the pulse current, making the current vertically introduced into the magnesium/titanium composite slab with the large thickness ratio from the upper part of the plate surface, wherein a current density is 150-500 A/mm 2 , a frequency is 300-1000 Hz, a power is 10-50 KW, a duty cycle is 20%-60%, waveform is rectangular; and meanwhile, turning on a warm roller device to carry out an induction heating on a roller, and starting rolling after a heating temperature reaches a rolling temperature of the magnesium/titanium composite slab with the large thickness ratio, wherein the heating temperature is 400-500° C.; 
 step 3, rolling and bonding 
 rolling the magnesium/titanium composite slab with the large thickness ratio heated to the rolling temperature by adopting single-pass rolling or multi-pass rolling, wherein a pass reduction rate is 20%-25% and a rolling speed is 0.1-0.5 m/s; and 
 step 4, post-treating the slab 
 annealing a rolled magnesium/titanium composite slab with a large thickness ratio, preserving heat, and furnace cooling, then polishing and cleaning a cooled magnesium/titanium composite slab with a large thickness ratio, and drying to obtain the magnesium/titanium composite slab with the large thickness ratio. 
 
     
     
       2. The pulse current-assisted roll bonding method for the magnesium/titanium composite slab with the large thickness ratio according to  claim 1 , wherein in the step  1 , an annealing temperature of the slabs of magnesium or magnesium alloy plate with large thickness is 300° C.-500° C., and a heat preservation duration is 30-60 min; an annealing temperature of the titanium thin plate is 800° C.-1000° C., and a heat preservation duration is 60-90 min. 
     
     
       3. The pulse current-assisted roll bonding method for the magnesium/titanium composite slab with the large thickness ratio according to  claim 1 , wherein in the step 1, a thickness of the intermediate transition layer foil is 0.1-0.5 mm; and
 slabs with a length of 100-300 mm and a width of 50-150 mm are cut. 
 
     
     
       4. The pulse current-assisted roll bonding method for the magnesium/titanium composite slab with the large thickness ratio according to  claim 1 , wherein in the step 2, the inert gas is argon atmosphere, an argon gas pressure is 0.95-1 MPa, and a mass purity of the argon gas is 99.99%. 
     
     
       5. The pulse current-assisted roll bonding method for the magnesium/titanium composite slab with the large thickness ratio according to  claim 1 , wherein in the step 4, an annealing temperature is 400° C.-500° C. and a heat preservation duration is 60-90 min.